Physiological responses of reared sea bream (Sparus aurata Linnaeus, 1758) to an Amyloodinium ocellatum outbreak

Amyloodiniosis represents a major bottleneck for semi-intensive aquaculture production in Southern Europe, causing extremely high mortalities. Amyloodinium ocellatum is a parasitic dinoflagellate that can infest almost all fish, crustacean and bivalves that live within its ecological range. Fish mortalities are usually attributed to anoxia, associated with serious gill hyperplasia, inflammation, haemorrhage and necrosis in heavy infestations; or with osmoregulatory impairment and secondary microbial infections due to severe epithelial damage in mild infestation. However, physiological information about the host responses to A.ocellatum infestation is scarce. In this work, we analysed the proteome of gilthead sea bream (Sparus aurata) plasma and relate it with haematological and immunological indicators, in order to enlighten the different physiological responses when exposed to an A.ocellatum outbreak. Using 2D-DIGE, immunological and haematological analysis and in response to the A.ocellatum contamination we have identified several proteins associated with acute-phase response, inflammation, lipid transport, homoeostasis, and osmoregulation, wound healing, neoplasia and iron transport. Overall, this preliminary study revealed that amyloodiniosis affects some fish functional pathways as revealed by the changes in the plasma proteome of S. aurata, and that the innate immunological system is not activated in the presence of the parasite.DIVERSIAQUA, Portugal [MAR2020]Fundacao para a Ciencia e Tecnologia [SFRH/BD/118601/2016]info:eu-repo/semantics/publishedVersio

Tissue-Specific Orchestration of Gilthead Sea Bream Resilience to Hypoxia and High Stocking Density

Two different O-2 levels (normoxia: 75-85% O-2 saturation; moderate hypoxia: 42-43% O-2 saturation) and stocking densities (LD: 9.5, and HD: 19 kg/m(3)) were assessed on gilthead sea bream (Sparus aurata) in a 3-week feeding trial. Reduced O-2 availability had a negative impact on feed intake and growth rates, which was exacerbated by HD despite of the improvement in feed efficiency. Blood physiological hallmarks disclosed the enhancement in O-2-carrying capacity in fish maintained under moderate hypoxia. This feature was related to a hypo-metabolic state to cope with a chronic and widespread environmental O-2 reduction, which was accompanied by a differential regulation of circulating cortisol and growth hormone levels. Customized PCR-arrays were used for the simultaneous gene expression profiling of 34-44 selected stress and metabolic markers in liver, white skeletal muscle, heart, and blood cells. The number of differentially expressed genes ranged between 22 and 19 in liver, heart, and white skeletal muscle to 5 in total blood cells. Partial Least-Squares Discriminant Analysis (PLS-DA) explained [R2Y(cum)] and predicted [Q2Y(cum)] up to 95 and 65% of total variance, respectively. The first component (R2Y = 0.2889) gathered fish on the basis of O-2 availability, and liver and cardiac genes on the category of energy sensing and oxidative metabolism (cs, hif-1 alpha, pgc1 alpha, pgc1 beta, sirts 1-2-4-5-6-7), antioxidant defense and tissue repair (prdx5, sod2, mortalin, gpx4, gr, grp-170, and prdx3) and oxidative phosphorylation (nd2, nd5, and coxi) highly contributed to this separation. The second component (R2Y = 0.2927) differentiated normoxic fish at different stocking densities, and the white muscle clearly promoted this separation by a high over-representation of genes related to GH/IGF system (ghr-i, igfbp6b, igfbp5b, insr, igfbp3, and igf-i). The third component (R2Y = 0.2542) discriminated the effect of stocking density in fish exposed to moderate hypoxia by means of hepatic fatty acid desaturases (fads2, scd1a, and scd1b) and muscle markers of fatty acid oxidation (cpt1a). All these findings disclose the different contribution of analyzed tissues (liver >= heart > muscle > blood) and specific genes to the hypoxic- and crowding stress-mediated responses. This study will contribute to better explain and understand the different stress resilience of farmed fish across individuals and species

A new type of lordosis and vertebral body compression in Gilthead seabream, Sparus aurata Linnaeus, 1758: aetiology, anatomy and consequences for survival

A new type of vertebral malformation is described, consisting of deformed cartilaginous neural and haemal processes and the compression and fusion of vertebral bodies. The malformation is designated as haemal vertebral compression and fusion (haemal VCF). We studied the aetiology of the malformations and described microanatomical histopathological alterations. The malformations were detected during routine quality control in one of six monitored Gilthead sea bream populations. Haemal VCF affected the posterior part of the vertebral column (haemal vertebrae). In 20% of the deformed specimens, haemal VCF was combined with lordosis. At 35dph (days post-hatching), early anatomical signs of the haemal VCF consisted of abnormal centrum mineralization, malformed cartilaginous neural and haemal processes and developing lordotic alterations. The histological examination of the deformed individuals revealed that haemal VCF is preceded by notochord abnormalities. The frequency of deformed individuals was three times higher at 35 than at 61dph (50.3% vs. 17.2%, n=157 and n=250, respectively). No signs of repair or reversion of malformations have been observed. Thus, the steep decrease in deformities in older animals suggests that haemal VCF is linked to high mortality rates. The results are discussed in respect of the possible causative factors of haemal VCF

Sustainability vs. Quality in gilthead seabream (Sparusaurata L.) farming: are trade-offs inevitable?

European aquaculture industry should be at the forefront of sustainable development, providing healthy and safe food of the highest quality to the consumer, through an environmentally sound approach. The purpose of this review was to explore in what way the current drive for sustainability has affected what the consumer perceives as quality in fish, specifically in gilthead seabream, one of the most important farmed species in the Mediterranean. It focuses on nutritional aspects such as fish meal and fish oil replacement, quality tailoring through finishing strategies, the influence of different farming systems and the effect of slaughter stress on seabream quality. In general, fish meal and fish oil replacement with vegetable ingredients will result in changes in the fatty acid profile of the fillets, and consequently the potential health benefits seabream offers to the consumer. While organoleptic properties suffer little change, the impact of these ingredients on welfare has not been fully investigated. Further studies are also needed to evaluate the effect of land animal ingredients on seabream quality. In either case, although finishing strategies to restore essential fatty acids are not completely effective, seabream can still retain a high nutritional value. Information on the use of dietary supplements as finishing strategies is still extremely scarce. Regarding fish welfare, the high densities practised in intensive production systems pose concerns which warrant further research in this area. Furthermore, new alternatives for common harvesting and slaughter methods are needed to improve welfare, as traditional methods are clearly stressful.FCT, Portugal [SFRH/BD/40886/2007, SFRH/BD/41392/2007]info:eu-repo/semantics/publishedVersio

Gilthead sea bream

Two investigations were carried out with 150 g gilthead sea bream Sparus aurata to determine the relative activity of six digestive enzymes (pepsin, trypsin, chymotrypsin, carboxypeptidase A, carboxypeptidase B and amylase) and the pH variation in the lumen of different parts of the gut of fish fed one or two meals per day. Pepsin activity was found exclusively in the stomach, whereas activities of the other enzymes studied were found in all regions of the gut, including the stomach. The lack of localization of enzyme production in the digestive tract of S. aurata is similar to many other species as reported in the literature. The pH variations found in the different regions of the gut could be explained by general digestive physiology following the flow of digesta along the digestive tract. The range of pHs recorded in the various regions of the gut were generally outside the cited optima for many digestive proteases in this species.peer-reviewe

Sonophoresis efficiency: consequences of methyl donors supplementation at early developmental stage in gilthead seabream (Sparus aurata). Effects on growth, nutrient metabolism, egg and larval quality, and methylation patterns of larvae and juvenile fish

Dissertação de mestrado, Aquacultura e Pescas, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2016It is essential that the vegetable ingredients that will be use in Aquaculture feeds can maintain the growth parameters in fish when compared with the fish meal diets. Studies have shown that the replacement may be achieved until a certain level without affecting the growth parameters. Sometimes the vegetable diets lack essential amino acids that need to be supplemented in the feeds, one of the amino acids that sometimes is lacking is the Methionine. In this study the gilthead seabream (Sparus aurata, L. 1758) eggs were supplemented with Methionine to understand if the supplementation had an effect in the larvae growth. The supplementation was performing using the innovative technique Sonophoresis. The amount of Methionine that entered the supplemented eggs was 33.1- fold higher than in the eggs that were not supplemented. Due to the supplementation the oil globule area of the larvae of the treatment MET was higher in the 2 and 4 days after hatching (DAH), also the dry weight was higher in the larvae of treatment MET during the first week. After the first week the larvae of both treatments presented similar growth parameters so a later supplementation was planned and performed at 57 DAH. This second supplementation was done using a Vegetable feed (VEG) supplemented with methionine. At the end of the experiment the juveniles that were from the eggs supplemented and were fed with VEG diet (METVEG) presented higher condition factor (K). In conclusion the Sonophoresis technique was a success, which allowed the alteration of the composition of the egg with the methionine, the early supplementation was able to promote growth in gilthead seabream larvae. The VEG diet did not negatively affected the survival and promoted fish to achieve similar weight to the FM diet

Protein changes as robust signatures of fish chronic stress: a proteomics approach to fish welfare research

Background Aquaculture is a fast-growing industry and therefore welfare and environmental impact have become of utmost importance. Preventing stress associated to common aquaculture practices and optimizing the fish stress response by quantification of the stress level, are important steps towards the improvement of welfare standards. Stress is characterized by a cascade of physiological responses that, in-turn, induce further changes at the whole-animal level. These can either increase fitness or impair welfare. Nevertheless, monitorization of this dynamic process has, up until now, relied on indicators that are only a snapshot of the stress level experienced. Promising technological tools, such as proteomics, allow an unbiased approach for the discovery of potential biomarkers for stress monitoring. Within this scope, using Gilthead seabream (Sparus aurata) as a model, three chronic stress conditions, namely overcrowding, handling and hypoxia, were employed to evaluate the potential of the fish protein-based adaptations as reliable signatures of chronic stress, in contrast with the commonly used hormonal and metabolic indicators. Results A broad spectrum of biological variation regarding cortisol and glucose levels was observed, the values of which rose higher in net-handled fish. In this sense, a potential pattern of stressor-specificity was clear, as the level of response varied markedly between a persistent (crowding) and a repetitive stressor (handling). Gel-based proteomics analysis of the plasma proteome also revealed that net-handled fish had the highest number of differential proteins, compared to the other trials. Mass spectrometric analysis, followed by gene ontology enrichment and protein-protein interaction analyses, characterized those as humoral components of the innate immune system and key elements of the response to stimulus. Conclusions Overall, this study represents the first screening of more reliable signatures of physiological adaptation to chronic stress in fish, allowing the future development of novel biomarker models to monitor fish welfare.This study received Portuguese national funds from FCT - Foundation for Science and Technology through project UIDB/04326/2020 and project WELFISH (Refª 16–02-05-FMP-12, “Establishment of Welfare Biomarkers in farmed fish using a proteomics approach”) financed by Mar2020, in the framework of the program Portugal 2020. Cláudia Raposo de Magalhães acknowledges an FCT PhD scholarship, Refª SFRH/BD/138884/2018. Denise Schrama acknowledges an FCT PhD scholarship, Refª SFRH/BD/136319/2018.info:eu-repo/semantics/publishedVersio

What determines growth potential and juvenile quality of farmed fish species?

Enhanced production of high quality and healthy fry is a key target for a successful and competitive expansion of the aquaculture industry. Although large quantities of fish larvae are produced, survival rates are often low or highly variable and growth potential is in most cases not fully exploited, indicating significant gaps in our knowledge concerning optimal nutritional and culture conditions. Understanding the mechanisms that control early development and muscle growth are critical for the identification of time windows in development that introduce growth variation, and improve the viability and quality of juveniles. This literature review of the current state of knowledge aims to provide a framework for a better understanding of fish skeletal muscle ontogeny, and its impact on larval and juvenile quality as broadly defined. It focuses on fundamental biological knowledge relevant to larval phenotype and quality and, in particular, on the factors affecting the development of skeletal muscle. It also discusses the available methodologies to assess growth and larvae/juvenile quality, identifies gaps in knowledge and suggests future research directions. The focus is primarily on the major farmed non-salmonid fish species in Europe that include gilthead sea bream, European sea bass, turbot, Atlantic cod, Senegalese sole and Atlantic halibut

Variations of biofouling communities in an off-shore fish cage farm from North-Western Sardinia = Variazioni del biofouling in un allevamento ittico in gabbie off-shore della Sardegna nord-occidentale

Biofouling variations were studied in a fish farming facility near Alghero (Italy) between November 2007 and November 2008. Net panels suitable for the settlement of encrusting organisms were immersed in cages in which large and small gilthead seabream specimens were reared. Significant differences in biofouling biomass and coverage were observed between cages containing fish and controls. The results obtained revealed that gilthead seabream can exert a crucial role in controlling biofouling growth, independently from its size